Mark Lamonica: Alright. Confusion about Fidelity money market funds. My coworker was recently telling me about putting money into a Fidelity money market fund instead of just holding it in bank savings account, told me it's yielding 2% right now. However, when I look on Fidelity's app, it's year-to-date is only showing 0.37%, but the 7-day yield says 2.09%. Confused by this, can someone help me understand what is the true yield I'll be getting if I put my money in this fund?

Alright. So it's a good question and the answer is, nobody knows. So it's important to talk about how a money market fund actually works. So money market funds invest in very short term securities. These are fixed interest securities and because they're so short term, of course their interest rate changes as interest rates change. So, in a year where we've had rising interest rates, it makes sense that the year-to-date yield is a lot lower than that 7-day yield. And what that 7-day yield is supposed to do is obviously look back over 7 days and then annualize what you've gotten in that money market fund. And that's the best approximation we can have for what that fund is currently yielding.

The issue, of course, is over the course of the year or over the course of however long you hold that fund interest rates will of course continue to fluctuate. If they go down, you'll earn less. If they go up, you'll earn more. So that's what you should expect out of investing in a money market fund.